Golang : Get all upper case or lower case characters from string example


You have a string and you want to get all the uppercase characters in the string. For example, you want to get the characters of A,O and H from the string "Ace Of Hearts" and use the AOH to make a key for your string map. How to do that?


Use unicode.IsLower() function to determine if the character is lowercase or not. If not, then push the characters into a slice or form a string with strings.Join() function.

Here you go!

 package main

 import (

 // faster way to get rid delimiters
 // for string without unicode

 func removeDelimString(str string) string {
 // alphanumeric (== [0-9A-Za-z])
 // \s is a white space character
 regExp := regexp.MustCompile(`[^[:alnum:]\s]`)
 return regExp.ReplaceAllString(str, "")

 // get all upper case characters from string
 // to get all lower case characters, just remove the exclamation mark !
 // infront of unicode.IsLower()

 func getUpperCaseChars(str string) []string {

 tokens := removeDelimString(str)

 var result []string

 for _, char := range tokens {

 if !unicode.IsLower(char) && char != ' ' {
 result = append(result, scanner.TokenString(char))

 return result

 func main() {
 str := "This a string with some UpperCase Characters."

 temp := getUpperCaseChars(str)

 for k, v := range temp {
 fmt.Println(k, v)

 // form into a UPPERCASE string

 upper := removeDelimString(strings.Join(temp, ""))







0 "T"

1 "U"

2 "C"

3 "C"






  See also : Golang : Break string into a slice of characters example

By Adam Ng

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